Hi all!
I am currently trying to chase some problems in an n-way multi-master
setup with three servers. We have used the instructions at
http://www.openldap.org/doc/admin24/replication.html#N-Way%20Multi-Master
as our guidance and we are using OpenLDAP version 2.4.11.
The result we see currently is that replication works only partially,
with some strange errors here and there.
As I believe it will be pointless to post all our cn=config LDIF here
and explain scenarios which work and those which don't, I thought it
would be more productive to double-check that I have correctly
understand what I *should* be seeing happen on my systems and how I can
properly monitor this. My problem may be that I still need to learn how
to properly monitor my slapd.
To begin with, I would just ask for confirmation of my proper
understanding of the documentation:
1. A master server is a server which is using the syncprov overlay
(servers/slapd/overlays/syncprov.c). This overlay will do little more
than just provide a synchronization cookie (CSN) which consumers may ask
for to find out what needs to get replicated and what not.
2. A consumer server is a server in which an additional thread is
running which will query the master(s) in a given interval to ask for
updated and if any, get them over the wire and into the local copy of
the database. This synchronization thread is servers/slapd/syncrepl.c I
guess?
3. An N-Way Multi-Master setup is a setup in which N servers are each a
master and any of the others is a consumer of all other masters?
I am I right up to here?
So what I fail to understand is:
1. What is the difference between Mirror Mode and N-Way Multi-Master?
Especially given that in N-Way Multi-Master, have to set olcMirrorMode
to TRUE.
2. Given that I have added a 'Sync' value to the olcLogLevel attribute,
what would be the "health check" information I should be watching in the
log for to see that replication is attempted as expected.
3. What problems should I be watching for in the logs?
4. Could I for example manually ask a master (using some ldapsearch
statement, pretending I was the consumer) what the master thinks which
entries I would have to update?
Regards,
Torsten